So, I guess we stick with the menu sequence I proposed. That's an overwhelming majority.

Today was spent filling in the setup menus with writes to the registers. Everything is going well and I'm still under 3000 bytes (barely). Also, I was able to get the register read routine working after a bit of diddling. I'm actually holding back a bit; it was a long day of debugging, but it turned out that problem was me, not the circuit. Anyway, it all works now.

I do have all of the menu setup stuff done now and can report that the output is dead on with respect to frequency. I'm quite stunned. When I punch in 100 Hz, that's exactly what I read on the counter, and likewise for all other values. On the other hand, the match to the equally tempered scale is dicey above 1 kHz in places.

Thanks, THeff, for your update. It's good to know someone is actually trying this out. The hardware and software work amazingly well, don't you think? I had originally thought that gremlins would constantly haunt us, but actually the AY chip cooperates with the Picaxe pretty well so far. To your ears, how does the tuning sound when you try your test MIDI program? Thanks again for actually trying this stuff out. I wish we could get others involved to spread the labor out.

This fell lower on my priority stack when it didn't seem like firmware development would be visible, but I just completed another project that's been sucking up time (which also frees up the second big breadboard if I need it) so I should have time to actually test along side THeff starting this week. I need to catch up with the circuit mods and additions (output for audio and such) and I expect to be ready to go tomorrow night.

If anyone is working with the picaxe from a MAC I would appreciate it if you can PM me. I don't want to hijack this discussion with personal troubleshooting (though I will probably report back what finally fixes it). I've ripped the picaxe down to the bare minimum, I'm getting "Hello..." messages and can read the firmware, and I've tried all kinds of variations but still no luck getting the download to go. I'm about to the point of abandoning the sparkfun USB adapter in favor of either 1) the arduino usb/serial which can be used for picaxes with a couple additions or 2) a totally different serial solution.

I'm using the Sparkfun USB/PicAxe adapter also. I'm not sure if it matters but I terminated the FTDI RX/TX pins just like the axe027 cable that PicAxe sells. They have a series 100 ohm resistor and a 10k pull down resistor (on the PicAxe side) on both pins. Sparkfun left the RX/TX pins open and unterminated. Make sure you are not using the 22K series resistor that is for an RS232 level port. Check out the bottom of the PDF that I attached.

Thomas,

Did you get the noise to work? I think I only changed about four or five lines of your AY-Frequency_demo program for the noise test program.

Since the sparkfun adapter is SMD, are you doing the termination at the breadboard end of things?

I just finished making a "real" serial cable, DB9 -> stereo jack, and I'm about to go try and figure out where I stashed my USB->RS232 adapter from years ago (just had it out this week though, was shuffling stuff). If I can't get that method to work, then I will come back to this sparkfun beastie and try to use your suggestions.

I put the resistors on the breadboard not the Sparkfun adapter. You don't want to use the 22k because it is there to level shift the PC serial RS232 from +12v down to +5V and shunt the -12V at the PIC. The FTDI chip on the Sparkfun board is already at a 5V TTL level.

I believe the 100 ohm/10k resistors are there to prevent ringing on the long cables.

The good news: my hand built DB9 cable works great as is, so I think I'm not going to mess with success . I have a blinking light, it's late-ish, I was up too late last night, and I have an early day tomorrow, but I'm optimistic that I will be in business soon.

I will probably at some point test the sparkfun with those changes just to be able to close the loop for anyone following along, but I want to hear sounds first

I was looking at the axe027 document again and they say you can leave the 22K resistor there even when using the USB cable. It also says you can reduce it to 1k if you want, but they recommend leaving this resistor there just in case you should happen to use a PC serial cable at some point. 22k seems like a lot of series resistance if you are connecting TTL to TTL.

I suppose I should mention that when I tried a USB to COM adapter (four bucks from Amazon!) it worked like a champ on an XP machine but was quite erratic under Windows Seven. That's when I discovered Revolution Education has their own driver. After installing it, the adapter worked well on both machines. So even if your adapter comes with its own driver (mine did), ignore it and use the one from Rev Ed.

I have some really bad news. The AY-3-8910 that I have been using has a date code of 1982 and the noise works fine. I just bought four newer chips from BG Micro with a date code of 0426 (2004 I guess) and the noise does NOT work on any of these chips!

The three tone outputs worked on the first 2004 chip that I tested and I assume on the other three but I did not test the tones on those yet.

Of course "works" is qualified with "to blink an LED" because I was starting at the beginning to be sure I had things working, since it didn't work first thing out the gate. Not clear whether my previous wiring job or some other gaffe caused the premature demise, but I will proceed slowly and test each step of the way. And order some more backups.

BTW, both of mine are the 0426 date code, though obviously I haven't tested the noise.

I did try the envelope test this morning and heard the steps of the DAC that you mentioned. I guess it sounds jagged just like the picture of the curves in the datasheet. This was with the older 1982 chip, so I guess it is the nature of the beast, not a defect. Using only 5 bits leaves a lot to be desired.

I'm starting to have some doubts about this project or at least what it's good for. In particular, I don't think that the envelope (four bits actually) is fine enough to be useable for most music. The thumping, presumably caused by the DC bias line shifting (starts at 0.5V and goes downward) interferes way too much with the tone. My assessment is that the envelope generator is good for nothing and we should phrase this circuit as though it were a VCO, adding the envelope afterwards in the usual analog fashion. It's too bad, for the exponential decay of the envelope is way better than the linear one of SN76477; it really trails off nicely.

My additional chips arrived today. Of the five I now have, only one could produce the noise. And two of them had screwed up IO ports, and one more no Tone A. Age seems to have had an effect on this part.

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